1. Field of the Invention
The present invention relates to a method of treating a substrate, for example, a semiconductor wafer or the like, a coating film removing apparatus, and a substrate treatment system.
2. Description of the Related Art
In photolithography processing in a process of manufacturing a semiconductor device, for example, resist coating treatment of applying a resist solution above a semiconductor wafer (hereinafter, referred to as a “wafer”) to form a resist film, exposure processing of exposing the resist film to light under a predetermined pattern, and developing treatment of developing the exposed resist film and so on are performed in sequence, to form a predetermined resist pattern above the wafer. Etching treatment of the wafer is performed using this resist pattern as a mask, and stripping processing of the resist film and cleaning of the wafer are then performed to form a predetermined pattern on the wafer. The process of forming a predetermined pattern in a predetermined layer is generally repeatedly performed 20 to 30 times to manufacture a semiconductor device.
Out of these treatments and processing, the above-described exposure processing is performed, for example, by applying ArF laser, KrF laser, or the like to the resist film on the wafer with the rear surface of the wafer being suction-held by a chuck in the apparatus for performing the exposure processing. If, for example, contaminants adhere to the rear surface of the wafer when the exposure processing is performed, the wafer is not horizontally held by the chuck, thus causing defocus during the exposure processing. Accordingly, it is necessary that the wafer is horizontally held by the chuck, that is, the rear surface of the wafer sucked by the chuck is flat, in order to appropriately perform the exposure processing.
Hence, a scribing apparatus including a transfer arm for inverting the front and rear surfaces of the wafer, a freely rotatable spin chuck for holding the wafer, and a scribing brush for cleaning the front and rear surfaces of the wafer held by the spin chuck has been conventionally proposed as an apparatus for removing the contaminants on the rear surface of the wafer. Conventionally, before performance of the exposure processing for the wafer, the scribing apparatus is used to first direct the rear surface of the wafer upward by means of the transfer arm and hold the wafer in this state by means of the spin chuck. The scribing brush is brought into contact with the rear surface of the wafer while rotating the spin chuck is rotating, thereby removing the contaminants adhering to the rear surface of the wafer (Japanese Patent Publication Laid-open No. Hei 3-52226).
However, even if the contaminants on the rear surface of the wafer are removed, minute scratches may be generated on the rear surface of the wafer during various kinds of treatments and processing in the process of manufacturing the wafer to cause projections and depressions on the rear surface of the wafer. Especially when the etching treatment is performed, the rear surface of the wafer is likely to get minute scratches if the surface temperatures of the wafer and the electrostatic chuck are increased during the etching treatment due to the difference in coefficient of thermal expansion between the wafer and the electrostatic chuck holding the wafer. Due to such minute scratches on the rear surface of the wafer, the wafer is not horizontally held during the exposure processing, thus causing defocus.